Telephone-exchange system.



C. L. GOODRUM.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. I7. 1917.

Eatented Sept. 10, 1918 Cha //1 yen/0k r/es A. 5004mm? in sas PATENT @FFIQ.

CHARLES LANE GOODRUM, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK,

N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

To all whom it may concern Be it known that I, CHARLES L. GooDRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems, and more particularly to circuit arrangements for selector switches employed in automatic or semi-automatic telephone exchanges.

It is the object of this invention to provide an arrangement fora final selector or connector switch, especially adaptable for use in private branch exchange telephone systems, by the use of which, it is possible for a called party to hold a connection, call a third party and after disconnecting the third party, return to the original connection.

According to this invention the calling subscriber in a full automatic or an operator in a semiautomatic sends out impulses to set up a connection through selector and connector switches with the desired party. If the called party, for any reason wishes to converse with a third party, the impulse sending device at the called station is operated to send out a predetermined number of impulses. This causes the talking conductors leading to the called station to be disconnected and the called station may in the usual manner call any desired station in the system. After conversation is completed the receiver is replaced momentarily upon the switchhook, which action disconnects the third party and connects again the calling party. Upon termination of conversation the switching apparatus is returned to normal position by the calling subscriber placing his receiver upon the hook. More specifically the connector switch is provided with a magnet, which performs the double function of moving the brushes of the side switch associated there with and of a cutoff relay for discornecting the called from the calling line during the time of calling and of conversation with the third party.

The drawing represents diagrammatically an automatic telephone exchange system,

Specification of Letters Patent.

"switch wiper 15 (first position),

Patented. Sept. 10, 1918.

Application filed September 17, 1917. Serial No. 191,765. 7

and more in detail the circuit of a final selector or connector switch, only so much being shown of the apparatus and circuits as is necessary for a clear understanding of the invention.

The subscriber at substation A desiring to establish a connection with a substation B, removes his receiver from the switchhook and operates a calling device 3 for extending his line by means of switching mechanism comprising a selector switch -l to an incoming line or trunk leading to a selector switch 5. A circuit is closed from grounded battery through the left hand winding of a line relay 6, the calling incoming line circuit and the right hand winding of relay 6, to ground. Relay 6 by attracting its armature closes an energizing circuit for a slow-acting relay 7.

The subscriber at substation A proceeds now to send out the tens and units impulses for controlling the setting of the final selector or connector. By operating the impulse sending device 8, the subscriber produces short interruptions in the incoming line circuit for intermittently deenergizing and energizing relay 6. In response to the first deenergization of relay 6 a circuit is closed from grounded battery through the winding of primary magnet 8, a wiper 9 of a side switch associated with connector 5, conductor 10, the front contact and armature of the relay 7, and the back contact and armature of relay 6 to ground. A further circuit is closed from ground through the armature and back contact of relay 6, conductor 10, conductor 11, wiper 1:2 (first position), and the winding of slow acting relay 13 to grounded battery.

In response to each denergization of relay 6, magnet 8 receives an impulse and causes the stepping of the connector brushes to select a group of outgoing lines in which the line leading to the called substation B is located. Relays 7 and 13 being slow to release, remain energized during the vibration of the armature of relay 6. Upon the energization of relay 13, a. circuit is closed from grounded battery through the lower winding of slow-acting escapement magnet 14, side the front contact and right hand armature of relay 1% and the back contact and armature of relay 16 to ground. Escapement magnet 14: be

' the side switch, primary magnet 8 is discon nected and the secondary magnet 17 is connected in the circuit.

The subscriber at substation A now proceedsto send out the units impulses. Relay.

13 and magnet 14 become energized in the same manner as above described, but the impulses repeated by relay 6 are transmitted to a secondary magnet ,17 instead of-to the primary magnet 8.

\ Under the control of magnet 17 the brushes of connector 5 are stepped onto the line leading to the called substation B. After the sending out of the units-impulses, relay 6 retains its armature attracted and opens the circuit of relay 13. Relay 13 releases and opens the circuit of magnet 14, which is made slow to release, so-that the desired line is tested before magnet 14 releases. As soon as the test brush 21 reaches terminal 20 individual to the called station, and if thisstation is not engaged in conversation as a calling or called subscriber, a circuit is established from grounded battery through winding of relay 40, terminal 20, brush 21,

side switch wiper 22 (second position), conductor 23, left hand armature and back contact of relay 13, right hand winding of relay 24, to grounded battery. This circuit is closedbefore escapement magnet 14 is-released. The called line being idle, relay'24 does not become energized due to the circuit just traced. The circuit of slow release magnet 14 is opened by the denergization of relay 13. Magnet 14 becomes denergized and moves the side switch brushes into position 3. In position 3 of the side switch, a circuit is closed from grounded battery, ringing current generator 25, winding of slow acting 'relay 16, side switch wiper 26, back contact and lower armature of'escapement magnet 14, the called substation loop, upper outer' armature and back contact of escapement magnet 14, side switch wiper 27, to ground, for, signaling the called station. A further circuit is closed frompgrounded battery,

winding of relay 13, side l-s'witchwiper 12, front contact and armature of relay '6, to

ground. As soon as the called subscriber removes his receiver from the switchhook, re-

" lay 16 becomes energized and closes thecircuit of escapement magnet 14, whereupon the side switch wipers are moved into gposi tion 4 due to the following circuit being and a circuit for the release magnet 30 is closed from grounded battery, through the closed. Grounded battery, lower winding of magnet 14, sideswitch wlper 15 (third position), front contact and armature of relay 16 to ground. It should be noted that the teeth on the escapement magnet are so arranged that in positions 1 and 2 of the side switch the wipers are moved forward on def energization of the escapement magnet while in position 3 the wipers are moved forward on energization. v In positions 3 and 40f the side switch a ground is connected through the side switch wiper 22 to terminal 20 and the multiples thereof for making the selected lines inaccessible to other incoming calls. v I

Upon the termination of the conversation, the calling subscriber replaces his receiver upon the hook, opening thereby the circuit of relay 6. Relay 7 becomes deenergized winding of release magnet 30, off normal contact 31, back contact and armature of relay 7 and back contact and armature of relay 6, to ground. This circuit remains closed as long as contact 31 is closed, 71. e., until connector-5 returns to its normal'posi tion, magnet 30 causing the restoration of the side switch and connector 5 to normal.

If the called line is busy, 2'. e., if ground is connected to terminal 20, the above traced circuit of relay 24 results in the energization pofthis relay. Relay 24' closes a locking cir cuit for itself from grounded ,battery through the left hand winding, front contact 0 and inner left hand armature thereof and through the front contact and armature of relay 6, to ground. A circuit is also closed from ground through the secondary wind ing'of inductance coil 48, right-hand 'arma ture and front contact of relay 24, conductor 52, the calling sub-station loop and the left hand winding of relay 6 to grounded battery. A characteristic signal is sent to the calling substation from an alternating m source 51 for indicating the busy condition of the desired line.

, The calling subscriber restores his receiver to the switchhook opening thereby .the incoming-line circuit. Relays 6 and 7 become 15 deenergized and a circuit for release magnet 30 is established from grounded battery, through winding of release 'magnet 30, off normal contact 31, back contactand armature of relay 7 and back contact and arma- 12c ture of relay 6 to ground. Magnet 30 becomes energized and causes the restoration of t5he side switch wipers and the connector Selector-4 and the other apparatusemployed in the building up of the connection are restored to normal many well known manner.

Assuming that the subscriber at substation B desires to comersewith the subscriber at substation C, it is necessary that his cut-ofi relay 40 be denergized in order to reconnect the line relay 41 to his line. This is accomplished by the subscriber at substation B operating his sending device 42 to transmit any desired number of impulses. When the relay 28 denergizes in response to. the impulses from the sending device 42 the slow releasing relay 13 becomes energized over a circuit extending from grounded battery, Winding of rela 13 side switch wiper 12 (fourth position front contact and armature of slow release relay 18, back contact and armature of relay 28, back contact, upper inner armature of escapement magnet 14 and back contact thereof to ground. The relay 13 attracts its armature and closes a circuit for escapement magnet 14, throughground, armature and back contact of relay 16, armature and front contact of relay 13, side switch wiper '15 (fourth position) lower Winding of escapement magnet 14, to grounded battery. Escapement magnet 14 is energized and its armatures are attracted, thus cutting ofl the called from the calling line.

The cutoff relay has its energizing circuit temporarily interrupted at the upper inner battery upper winding thereof, front contact and upper inner armature thereof, side switch wiper 22, .(fourth position) brush 21, terminal 20 and conductor 46 to ground.

When the subscriber at sub-station B desires to disestablish his connection with the subscriber at station C, be momentarily replaces his receiver on its switchhook. This causes the line switch and the other switches employed in establishing the connection to substation C to be restored in the well known manner. The release of the line switch causes the momentary deenergization of the cut-off relay 40 and also causes the deenergization of escapement magnet 14. The escapement magnet 14 upon deenergization again completes the conversational circuit between the subscribers A and B and the cutoff relay 40 and relay 28 are again energized.

At the close of conversation the restoration of the connector switch, which isunder interruptsthe energizing circuit of the slow releasing relay 7 causing it to retract its armature. An energizing circuit is thereupon completed for the release magnet 30. This circuit extends from grounded battery, winding of release magnet 30, off normal contact 31, back contact and armature of relay 7, and back contact and armature of rela 6 to ground.

What is claimed is:

1. In a telephone exchange system, a plu-v rality of stations, means including an automatic switch for interconnecting a calling and a called station, and a combined cutofi' relay and side-switch magnet for simultaneously disconnecting said called station from said calling station and forplacin said called station in condition to establish a connection to a third station.

2. In a telephone exchange system, a plurality of lines, means including an automatic switch for interconnecting a calling line with a called line, a combined cutofl relay and side-switch magent'arranged to disconnect said called line from said calling line and to place said called line. in con-' to place said called line in condition to 'establisha connection to a third line.

4. In a telephone exchange system, a plurality of lines, means for interconnecting a calling line with a called line, means associated with the called line for transmitting impulses, and a combined cutofi' relay and side-switch magnet arranged to be controlled by said impulse transmitting means to simultaneously disconnect said calling line from said called line and to place said called line in condition to establish a connection to a third line.

5. In a telephone exch System Ca ing line, a called line, a third line, impulse transmitting means, means including an automatic switch for connecting said calling line with said called line, means including a combined cutoff relay and side-switch magnet controlled by said impulse transmitting means for disconnecting said called line from said calling line and for lacing said called line in condition to esta lish a connection to said third line, means for establishing said connections to said third line, means to release said last'mentioned connection, and means controlled by said disconmotion for actuating said combined cutofi relay and side-switch magnet to reestablish communication between said calling and called lines.

6. In a telephone exchange system, a calling line, a called line, a third line, a nonnumerical switch associated with said called line and normally arranged to be operated by the removal of the receiver of said called line, means including an automatic switch for connecting said calling line to said called line, means controlled by the establishment of said connection for rendering said nonnumerical switch inefiective, means under the control of the calling line for releasing called line for transmitting impulses, and a combined cutoff relay and side-switch mag-' net arranged to be controlled by said impulse transmitting device for disconnectlng said called line from said calling line and for rendering the non-numerical switch associated with the called line operative to enable said called line to establish a connection to said third line.

In Witness whereof I hereunto subscribe my name this 13th day of September, A. D.

CHARLES LANE GOODRUM. 

